Art of forming molds.



No. 859,120. PATENTED JULY 2, 1907; G. R. SGHMIDT. ART OF FORMING MOLDS.

APPLIOATION FILED DBO.11.1906.

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W1 TNESSES PATENTED JULY 2, 1907.

0. R. SCHMIDT. ART OF FORMING MOLDS.

APPLIOATION FILED DEO.11,1906.

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CHARLES R. SCHMIDT, OF BALTIMORE, MARYLAND.

ART OF FORMING MOLDS.

Specification of Letters Patent.

Patented July 2, 1907.

Application fil d December 11,1906. seeiei No. 347,393.

To all whom it may concern:

Be it known that I, CHARLES R. SCHMIDT, a citizen of the United States,residing in the city of Baltimore and State of Maryland, have inventedcertain new and useful Improvements in the Art of Forming Molds, ofwhich the following is a specification.

This invention has relation to the art of forming molds by thecompacting in a suitable flask or mold of sand or other comminutedmaterial such as concrete to form building blocks or mixtures of sandand cement so as to cause the gradual formation of a mass conforming toa pattern or to the interior surfaces of a mold.

Heretofore in compacting finely comminuted material such as concrete ,orgreen sand, to form molds it has been the practice to shovel thematerial into a box to form the mold and to ram it down untilcompactness and density were obtained. According to this practice it hasbeen impossible to secure such density and homogeneousness of thecompacted material as would produce wholly desired or uniform results.

The principal object of my invention is to provide an economical andreadily available and practicable method of filling and compactingconcrete, sand or other material in a mold or flask, which can becarried into operation without the use of skilled labor or expensiveapparatus and which will not only produce molds of uniform density andhomogeneity with their attending advantages, but will allow of thedegrees of density and compactness being regulated to meet v.-- ryingconditions occurring in the practice of the art of molding.

In carrying my invention into effect I propose to fill a mold andcompact the material therein by allowing the sand or concrete to fallinto the mold box or flask from a height dependent upon the plasticityof the material, the degree of compactness to be obtained and thecapacity of the falling material to compact or cohere. I have found thatplastic or semi-plastic material when passed through a riddle anddropped from a sufiicient height will be divided by the riddle into'small masses or pellets of aggregated particles or grains and that uponfalling into a mold-box or flask, these masses or pellets will becrushed or flattened without being scattered and will be compactedtogether in equal degrees, thus forming a filling for a mold of auniform density and homogeneity impossible of attainment by any othermethod. The degree of density obtainable depends 1st, upon the regulatedsize and weight of the gravitating pellets. 2nd. upon the consistency ofthe material of which the particles or small aggregations are composed,and 3rd. upon the height from which they fall. These factors beingcontrollable, a mold of any desired density, fineness and compactnessmay be produced at will and the uncertainties and accidents ofhap-hazard work avoided.

In describing means for carrying my invention into effect it will beexpedient to refer to such an apparatus as may be employed in theformation of building blocks, or green sand molds and to refer to aplant in which the flasks or mold-boxes are conveyed from point to pointon trucks, each mold-box or flask being brought into requisition on themolding floor as required, filled, finished and removed.

The mold filling devices pertaining to my process of molding comprise anendless conveyer to lift the sand or concrete material from the moldingfloor to the desired height, a hopper in which the sand is dropped fromthe conveyer, a vertical chute leading from the hopper to a point abovethe flask, a measuring chamber, and a riddle or grid to separate themass of measured material into pellets of the desired size.

In the accompanying drawing, illustrating apparatus for carrying myinvention into effect, Figure 1 is an elevation of the sand conveyer,and dropper with ap purtenant mechanism, Fig. 2 is a vertical sectionalview. Figs. 3 and 5 are end views of part of the ap paratus. Fig. 4 is aside view of the mixing and mold filling apparatus.

l designates the floor of a mold room or foundry and 2 a mold-box orflask mounted on a truck 3 which, in Figs. 1 and 3. is shown as beingdirectly under the discharge end of the vertical chute 4. The chute 4 isaptly a rectangular elongated box like structure, and for the purposesof my invention it is preferable to construct this chute of a size, incross section, equal to the superficial area of the flask or mold. Thechute 4 is extensible at its lower part, and for this purpose isprovided with a sliding section 5, which embraces the lower end of thechute 4, and is supported by means of cords or chains 6 passing overpulleys 7 journaled on the chute 4, and carrying counterweights 8, 8, by

means of which the sliding section may be adjusted to suit the height ofthe mold-box or flask and held in position. The chute 4, rises to aproper heightsay 20 feet, more or less, and terminates in a hopper 9, atthe floor line of a gallery or elevated platform 10.

Below the hopper 9, the chute is provided with a measuring chamber,which is formed by cutting an opening 11 in one side of the chute,incasing the chute at the same point in a sliding open ended box 12, andfitting to the box and chute a horizontally movable gate or valve 13,which forms a cut off within the chute, and which by moving the box 12up or down may be located at difierent points. The gate or valve 13 isoperated from the floor of the foundry by means of a lever 15 pivoted at16. Below the valve 13 is fitted a grid or riddle l6 composed ofreticulated bars, or a perforated plate, fitted to ways or guides andconnected by a pitman 17 to an eccentric 19, on the shaft of a powerdriven pulley 20, the object being to impart to the grid or riddle arapid reciprocation motion for the purpose of riddling the sand andcausing it to drop through the interstices from the measuring chamber.The quantity of concrete material or sand constituting a charge for amold-box or flask is regulated by the capacity of the measuring chamberand this is graduated by the proper adjustment of the cut-off valve orgate 13.

The conveyer 21 is of any endless chain type provided with flights orbuckets 22, by which the concrete material or sand is liftedcontinuously from the floor or from a bin, above and to the hopper in apractically constant stream.

When the apparatus is intended for filling molds for building blocks, arotary mixing machine 23, is mounted on the stage or platform 10, withits outlet and adjacent to the hopper 9, so that the mixed concrete mayfall into the latter in a practically continuous manner. The forward endof the mixing tank has a hopper or filling chute 24, and to supply themixer with the ingredients of the concrete mixture in properproportions, two endless, bucket conveyers 26 and 27, are arranged atopposite angles so as to convey the materials from the floor or earthlevel to a point above the mixer and directly over its hopper or mouth.One of these conveyors will carry, saycement, and the other sandorrubble, and for whichever ingredient is used in the greatest proportion,the buckets of its conveyer will be proportionally larger than those ofthe other conveyer. By the use of the two conveyors the supply to themixing tank of the concrete, in the same relative proportion will beconstant and uniform.

It is to be remarked that by the method described of filling molds, theuniform compactness and density of the mass in the mold boxis insured,regardless of the depth or thickness of the mold, or of the block to bemolded. This cannot be accomplished by any process depending onpressure, such as ramming, packing or pounding, as in a mold of say 12inch depth, the pressure required is greatly in excess of what isnecessary to compact a depth of say six inches and even then the pointsof contact only are compressed hard, while the center of the massremains soft or imperfectly compressed.

I am aware that it has been proposed to form molds by dropping screenedor sifted material from a height into a mold box, and then consolidatingand facing off the material in the mold by-mechanical strikers, but thismethod differs radically from' my method, in which the material isdropped in the form of a shower or volley of pellets of such size thatthey will be crushed or flattened without being scattered and compactedto the required extent by gravity alone and will not require subsequentmanipulation. In fact I wish to avoid, as detrimental, the mechanicalconsolidating or facing off of the material which would impair thehomogeneous character of the mold.

Having described my invention, what I claim and desire to secure byLetters Patent- 1. The improvement in the art of forming molds, whichconsists in dropping the molding material into the mold in the form ofashower of soft pellets, from such height as will cause the pellets to becompressed by gravity alone into a compact mass of practically uniformdensity.

2. The improvement in the art of forming molds of plastic or semiplastic materials, which consists in measuring the exact quantity ofmaterial to fill or charge a mold or flask, depositing the measuredcharge upon and subjecting it to the action of a divider, ordistributing device, such as a grid or riddle, and dividing the massinto small pellets, regulating the size of said pellets, according tothe plasticity of the mass, and the height from which the pellets are tofall, and then dropping said pellets into a mold box or flask from sucha height that they will compact themselves together and fill the mold orflask.

3. The method of continuously mixing and molding concrete for theproduction of building blocks, consisting in continuously conveying theingredients of, the mixture in automatically regulated proportions to amixing ma chine, mixing the ingredients therein, delivering the mixtureto a vertical chute, measuring a charge for a mold therein, sub dividingthe measured mass into pellets, dropping the divided charge into a moldbox and concentrating and compacting the pellets by gravity into acompact mass.

4. The improvement in the art of forming molds, which consists inriddling and dividing a mass of the molding material into pellets anddropping a shower or volley of the pellets into a mold box from a heightsuificient to cause them to be crushed and compacted by the fall into acoherent mass of uniform density.

In testimony whereof I afiix my signature, in presence of two witnesses.

CHARLES R. SCHMIDT.

Witnesses 'lrros. A. Connonnv, .Tos. 13. Coxnonny.

